[vsnet-alert 56] further DV UMa eclipses

[tkato@kusastro.kyoto-u.ac.jp]

Dear vsnet-alert members,

    As D. Nogami has already announced, the Ouda team successfully obtained
V-band photometry of additional three eclipses of DV UMa, an SU UMa candidate
currently in rapid decline from a short (normal) outburst.

    The averaged magnitudes of DV UMa outside eclipses on these four nights
are given below.

     mid-UT    DV-comp  SD    N  band   V-mag
 ------------------------------------   -----
   950227.510  2.852   0.070  82  V      15.0
   950228.712  3.608   0.166  19  V      15.7
   950301.432  3.849   0.159  31  V      15.9
   950302.623  4.953   0.191  58  V      17.1

   comparison: GSC V=12.1 star

    A preliminary analysis of the eclipse light curves has yielded
following mid-eclipse times and eclipse depths.  This table also contains
the eclipse times on Feb. 27 for convenience.  The eclipse times were
not calculated for Feb. 28 and Mar. 1 observations due to the very poor
photometric condition.  Note that the asymmetry of the eclipse light
curves may have resulted a certain offset from the mid-eclipse times of
the white dwarf.

  mid-eclipse (JD-Geo)   depth(V)

      2449775.9651         1.6
          776.0509         1.7
          776.1365         1.9
          776.2224         2.0

      2449779.0557         5.1: (low S/N)
          779.1413        >3.4  (eclipse center was missed)
          779.2273         4.1

    On Mar. 3, DV UMa reached V = 21.7+/-0.5 at eclipse minimum.

    A least-sqares fit to the observed times of eclipse yieded a period
of 0.08585 +/- 0.00001 day (again internal error only), which is two sigma
longer than that obtained from Feb. 27 observations, but is still
significantly shorter than the published orbital period of 0.08597 day.
More observations (esp. in quiescence) are clearly needed whether this
discrepancy is caused by any asymmetric feature in the outbursting
disk, or by the error in the orbital period.

    We hope these eclipse times and period determination would be of any
help in scheduling the further observations.

Regards,
Taichi Kato

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